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Great Rift Valley

From Academic Kids

The Great Rift Valley is a vast geographical and geological feature that runs north to south for some 5,000 km, from northern Syria in Southwest Asia to central Mozambique in East Africa. The valley varies in width from 30-100 km and in depth from a few hundred to several thousand metres. It has been created through the rifting and separation of the African and Arabiantectonic plates that began around 35 million years ago in the north, and by the ongoing separation of East Africa from the rest of Africa along the East African Rift, which began about 15 million years ago. It was named by the explorer John Walter Gregory.

The southern end of the Red Sea marks a fork in the rift. The Gulf of Aden is an eastward continuation of the rift - before the rift opened, the Arabian Peninsula was attached to the Horn of Africa - and from this point the rift continues as part of the Mid-oceanic ridge of the Indian Ocean. In a southwest direction the fault continues as the Great Rift Valley, which split the older Ethiopian highlands into two halves.

In eastern Africa the valley divides into two, the Eastern Rift and the Western Rift.

The formation of the Rift Valley continues, probably driven by mantle plumes and ultimately a result of the African superswell. The associated geothermal activity and spreading at the rift has caused the lithosphere to thin from a typical 100 km thickness for continents to a mere 20 km. Within a few million years, the lithosphere may rupture and eastern Africa will split off to form a new landmass. If spreading continues, this will lead to the formation of a new mid-ocean ridge.

The Rift Valley has been a rich source of anthropological discovery, especially in Piedmont. Because the rapidly eroding highlands have filled the valley with sediments, a favourable environment for the preservation of remains has been created. The bones of several hominid ancestors of modern humans have been found there, including those of " Lucy", a nearly complete australopithecine skeleton, which was discovered by anthropologist Donald Johanson. Richard and Maeve Leakey have also done significant work in this region.